The prior art includes numerous prior art catch basin constructions. Some of these include inserts that range from simple geo-textile sheets placed at the grate opening to complex structures that include large water storage, various filters and grates.
The prior art structures have not been wholly satisfactory. Many prior art catch basin inserts are difficult to install and service. Many claim the use of absorbents but in practice they include a sock with absorbent material and only a small amount of hydrocarbons are captured from the drain water. Developed areas, such as malls or housing developments may have half a dozen sizes, shapes and types of catch basin inlets and the project ends up with a variety of inserts that make service difficult. Many of the prior art units quickly become ineffective because the filter strainer becomes plugged and most of the drain water overflows the unit and enter the storm drain system un-treated. Due to the great number of grate types and sizes including round, rectangular and square with various grate support frames, installation of inserts involves great expense and frequent failures occur. Most Inserts are supported from the catch basin frame with custom fabricated sheet steel formed to inset under the grate frame. This requires accurate measurements for each size and results in high costs that discourage installation.